What’s New in ICD-11: The Latest in Global Health Classification

Every time a doctor diagnoses a patient with diabetes, records a death due to a heart attack, or tracks a malaria outbreak, that information needs a common code so it can be understood anywhere in the world. That is exactly what the International Classification of Diseases (ICD) does, and its 11th revision, ICD-11, is the biggest upgrade this global system has seen in nearly three decades.

What is ICD-11 and why does it matter? 🔗

The ICD is maintained by the World Health Organization (WHO) and acts as the standard language for reporting diseases, injuries, and causes of death. ICD-11 was adopted at the 72nd World Health Assembly in May 2019 and officially came into effect on 1 January 2022, replacing ICD-10 after 30 years of use.

To understand the scale of this revision, consider the numbers. ICD-11 contains around 17,000 unique diagnostic codes, more than 120,000 codable terms, and supports over 1.6 million clinical situations through code combinations. Compared to ICD-10, which had roughly 14,000 codes, this is a massive expansion in detail and clinical accuracy.

Overview of ICD-11: what is genuinely new 🔗

ICD-11 is not just a longer list of diseases. It is structurally and technologically different from every version that came before it.

A digital-first design 🔗

Unlike its paper-based predecessors, ICD-11 is entirely digital, ready for use across multiple IT environments, and supported by a new Application Programming Interface (API). This means hospital software, electronic health records, and national health databases can plug directly into ICD-11 without manually copying codes from a book. The 2025 update added further upgrades like advanced natural language processing, API-based coding, improved error detection, and better spelling correction and language variation recognition.

A new coding structure 🔗

The code format has been redesigned. ICD-11 codes now run from 1A00.00 to ZZ9Z.ZZ, with four characters per category and two levels of subcategories. This alphanumeric structure gives much more room to grow as new diseases emerge, without running out of code space the way ICD-10 sometimes did.

Postcoordination and clustering 🔗

One of the smartest additions is postcoordination. Instead of forcing every clinical detail into a single code, ICD-11 allows coders to combine a main code with extension codes to capture severity, anatomical site, cause, and other nuances. A commentary in Health Affairs Scholar notes that postcoordination, advanced interoperability, and improved specificity make ICD-11 far more compatible with modern healthcare and digital information systems than ICD-10.

Multilingual support 🔗

Earlier ICD versions were dominated by English. The 2024 release expanded ICD-11 to 10 languages with ongoing efforts to extend its linguistic reach further, which is a meaningful step toward truly global usability.

Key disease categories in ICD-11 🔗

ICD-11 is organised into 26 chapters of disease groupings, plus a supplementary chapter for functioning assessment and another for traditional medicine. Several of these chapters are entirely new or significantly restructured.

Infectious diseases and neoplasms 🔗

The chapter on infectious and parasitic diseases has been refined to reflect updated microbiology and emerging threats. Neoplasms, the chapter covering cancers, now provides far greater specificity in tumour typing and improved coding for primary and secondary (metastatic) sites. This level of detail directly supports precision oncology and cancer registries, which are particularly important as cancer incidence rises in low- and middle-income countries.

Mental, behavioural and neurodevelopmental disorders 🔗

Chapter 6 has been substantially reworked. According to a paper in World Psychiatry, the mental health chapter now covers 20 groupings, including neurodevelopmental disorders, mood disorders, anxiety or fear-related disorders, disorders specifically associated with stress, feeding or eating disorders, and disorders due to substance use or addictive behaviours.

New categories that did not exist in ICD-10 include gaming disorder, complex post-traumatic stress disorder, and prolonged grief disorder. Personality disorders have been simplified into a single diagnosis with severity levels rather than fragmented subtypes, reflecting current clinical evidence.

New stand-alone chapters 🔗

ICD-11 introduces several chapters that did not exist in ICD-10, including disorders of the immune system, diseases of the blood and blood-forming organs, sleep-wake disorders, and conditions related to sexual health. The separation of sleep and sexual health into dedicated chapters was deliberate, intended to move past the outdated ICD-10 distinction between ‘organic’ and ‘non-organic’ conditions. Gender incongruence has also been moved out of mental disorders and into the sexual health chapter, a change widely viewed as a step toward depathologisation.

Traditional medicine: a historic first 🔗

For the first time ever, ICD-11 includes a supplementary chapter on Traditional Medicine Conditions. WHO explains that this chapter allows, for the first time, the counting of traditional medicine services and encounters, and measurement of their frequency, effectiveness, safety, quality, outcomes, and cost. It is meant for optional dual coding, not for mortality reporting.

This change is particularly relevant for India. On 10 January 2024, the Ministry of AYUSH and WHO jointly launched ICD-11 Traditional Medicine Module 2, which incorporates morbidity codes for Ayurveda, Siddha, and Unani systems into the global classification. According to DD News, examples of newly included terms span concepts like ‘Bhramaha’ in Ayurveda, ‘Ajal Kirkrippu’ in Siddha, and ‘Sadra-o-Dwar’ in Unani, grouped under broader categories like vertigo-related disorders. The Central Bureau of Health Intelligence (CBHI), the WHO Collaboration Centre for ICD activities in India, played a central role.

Implementation and global adoption 🔗

Bringing ICD-11 into everyday use across the world is a long, layered process. WHO has stressed that countries can continue using ICD-10 for as long as needed, but that delays may hamper global data comparability, interoperability, and the benefits of an up-to-date classification.

How countries are rolling it out 🔗

Adoption is uneven. Some countries became early adopters and started reporting mortality and morbidity data in ICD-11 soon after 2022. Others are taking longer because their health information systems are deeply tied to ICD-10. The United States, for instance, is expected to implement ICD-11 between 2025 and 2027 due to the complexity of its healthcare system, with the National Committee on Vital and Health Statistics setting up a dedicated ICD-11 Workgroup in 2023.

Common implementation challenges 🔗

A qualitative study published in BMC Medical Informatics and Decision Making looked at Malaysia’s national rollout and identified several recurring challenges that apply broadly. These include the complexity of ICD-11 itself, the need to customise it for local contexts, steep learning curves for vendors, outdated IT infrastructure, data duplication, workforce shortages, and the cost of retraining.

Other research highlights additional ground-level issues in many low- and middle-income settings, including irregular internet connectivity, erratic power supply, and inadequately trained clinical coders. These constraints matter because ICD-11 is built for digital workflows, and patchy infrastructure can blunt its advantages.

Why it still matters for health systems 🔗

Despite the hurdles, the value proposition is strong. Better coding means better data. Better data means more accurate disease surveillance, smarter resource allocation, fairer insurance reimbursement, and more reliable research. For a country like India, which is simultaneously battling infectious diseases, a rising non-communicable disease burden, mental health gaps, and a vast traditional medicine ecosystem, ICD-11 offers a single framework capable of capturing all of these realities in a comparable way.

What this means going forward 🔗

ICD-11 is not a one-time event. WHO releases annual updates, and the 2024 and 2025 editions have already added new conditions, refined existing categories, and improved digital tooling. As more countries cross over from ICD-10, the quality and granularity of global health data should keep improving. For students of population and family health studies, understanding ICD-11 is no longer optional; it is the language in which the next decade of health statistics will be written.

What do you think? Should India accelerate the full rollout of ICD-11 across all its public and private hospitals even if it means significant retraining costs, and how do you think the inclusion of Ayurveda, Siddha, and Unani in a global classification will shape the credibility of traditional medicine internationally?

References

1. https://www.who.int/news/item/11-02-2022-who-s-new-international-classification-of-diseases-(icd-11)-comes-into-effect
2. https://icd.who.int/en/docs/icd11factsheet_en.pdf
3. https://www.who.int/news/item/14-02-2025-who-releases-2025-update-to-the-international-classification-of-diseases-(icd-11)
4. https://academic.oup.com/healthaffairsscholar/article/3/3/qxaf037/8037567
5. https://www.who.int/news/item/08-02-2024-icd-11-2024-release
6. https://onlinelibrary.wiley.com/doi/full/10.1002/wps.20982
7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138088/
8. https://www.who.int/standards/classifications/classification-of-diseases
9. https://pib.gov.in/PressReleaseIframePage.aspx?PRID=1994614
10. https://ddnews.gov.in/en/who-launches-groundbreaking-icd-11-classification-integrating-traditional-medicine/
11. https://www.who.int/standards/classifications/frequently-asked-questions/icd-11-implementation
12. https://www.sprypt.com/blog/icd-10-vs-icd-11
13. https://bmcmedinformdecismak.biomedcentral.com/articles/10.1186/s12911-025-03157-7
14. https://www.solventum.com/en-us/home/health-information-technology/resources-education/blog/2023/12/innovative-approaches-to-icd-11-implementation-a-look-at-whats-working-around-the-world/